std::signbit
Defined in header <cmath> |
||
|---|---|---|
bool signbit( float arg ); |
(1) | (since C++11) (constexpr since C++23) |
bool signbit( double arg ); |
(2) | (since C++11) (constexpr since C++23) |
bool signbit( long double arg ); |
(3) | (since C++11) (constexpr since C++23) |
bool signbit( IntegralType arg ); |
(4) | (since C++11) (constexpr since C++23) |
1-3) Determines if the given floating point number
arg is negative.
4) A set of overloads or a function template accepting the
arg argument of any
integral type. Equivalent to
(2) (the argument is cast to
double).
Parameters
| arg | - | floating point value |
Return value
true if arg is negative, false otherwise.
Notes
This function detects the sign bit of zeroes, infinities, and NaNs. Along with std::copysign, std::signbit is one of the only two portable ways to examine the sign of a NaN.
Example
#include <iostream>
#include <cmath>
int main()
{
std::cout << std::boolalpha
<< "signbit(+0.0) = " << std::signbit(+0.0) << '\n'
<< "signbit(-0.0) = " << std::signbit(-0.0) << '\n';
}
Output:
signbit(+0.0) = false signbit(-0.0) = true
See also
|
(C++11)(C++11)
|
absolute value of a floating point value (\(\small{|x|}\)|x|) (function) |
|
(C++11)(C++11)(C++11)
|
copies the sign of a floating point value (function) |
C documentation for signbit |
|
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